1. Field of the Invention
Embodiments of the present invention relate, in general, to a barrel link and particularly to a barrel link compatible with standard barrels found in semi-automatic pistols.
2. Relevant Background
A semi-automatic pistol functions by using the energy from the recoil of a single round of ammunition to extract and eject a fired cartridge from the pistol's chamber and load an unfired round from a magazine into the chamber for the next shot.
Most types of semi-automatic pistols rely on a removable magazine for supplying new ammunition to reload the chamber to be able to fire the gun again. The removable magazine is most often located inside a hand grip. Typically, the first round is manually loaded into the chamber by pulling back and releasing (“racking”) the slide mechanism, after which the recoil operation of the pistol, when fired automatically, extracts, ejects, and reloads the chamber.
For a semi-automatic pistol, reload is typically accomplished by the recoil operation. This process can also be accomplished by harnessing gases produced when the gun is fired. In this case, the pistol siphons off some of the gases during the firing phase instead of relying on short recoil operation.
Self-loading automatic pistols can be divided into “blowback” and “locked-breech” categories according to their principle of operation. This classification roughly divides the operation into those specifically suitable for small-caliber versus large-caliber semi-automatic pistols.
In blowback semi-automatic pistols, generally .38 caliber (sometimes known as 9 mm Kurz, i.e., 9 mm Short) or smaller, the barrel is fixed to the frame and the slide or bolt; in its foremost position, it is held against the barrel only by the force of the recoil spring. The slide starts to move backwards immediately upon the gun being fired, as there is no locking action to hold the breechblock and slide locked with the barrel, even temporarily. At the appropriate point in the rearward motion, extraction and ejection of the fired brass of the cartridge are accomplished, and the used brass is typically ejected to the right of the pistol.
During the motion rearwards, the striker, hammer, or firing pin may be re-cocked. A spring, called a recoil spring, slows the movement of the slide as it is compressed. When the slide reaches the rear of its travel, the recoil spring is fully compressed (if not, the pistol may suffer a failure, called a “jam”). The slide begins to move forward under the force of the spring, stripping a new cartridge from the magazine and pushing the new cartridge into the chamber. Upon the slide's return to its fully forward position, the pistol is ready once more to be fired by squeezing the trigger. The mass of the slide must be sufficient to hold the breech closed until the bullet exits the barrel and the remaining pressure drops to a safe level. A cartridge with too high a pressure, or a slide with too little mass, can cause the cartridge case to extract too early; this causes a case rupture.
In contrast, in a locked-breech design (typically .32 caliber or larger) the barrel is temporarily locked to the slide. The most common locked-breech type is the short-recoil design. In a short-recoil pistol, the slide and barrel recoil together a short distance while locked together, until the cartridge-firing chamber pressure has dropped to a safe level. After sufficient travel to allow the bullet to exit and the pressure to drop, the barrel then unlocks from the slide, and the barrel's rearward motion is stopped. The ejection and loading of the new cartridge are similar to that in a blowback pistol. After the slide seats the new round into the chamber, the barrel begins to move forward with the slide, locking into place, at which point the cycle is complete.
FIGS. 1-3 show side projection cut away views of a Colt M-1911 semi-automatic pistol as is known in the prior art in various phases of operation. FIG. 1 shows a side projection cut away view of the Colt M-1911 ready for firing. FIG. 2 shows a side projection cut away view of the Colt M-1911 in the recoiled position. In a locked-breech design, the barrel 110 is locked during what is generally known in the art as link-up. Barrel link-up or link-up/cam-up in pistols occurs as the slide assembly 120 moves forward from the recoiled position and the barrel breech 135 contacts the breech face 140 of the slide 120 causing the barrel to pivot upward on the barrel link 150. This causes the locking lugs 155 on the top of the barrel to index with the corresponding locking recesses 160 in the slide. Barrel link-up/cam-up in M-1911 pistols with bottom barrel lugs is assisted by the cam action of the bottom front barrel lug surfaces as they bear on and cam upward on the slide lock cross pin 156.
Vertical barrel and slide locking occurs as the slide 120 causes the barrel 110 to swing upward on the barrel link 150. Aggregate barrel 110, slide 120, frame 170, and barrel link 150 dimensional tolerances determine the extent to which a given barrel will link upward and to which locking lugs 155 will vertically engage in any given M-1911 or similarly designed pistol. Locked slide position permits the barrel 110 to move upward and prepares the pistol for firing, as shown in FIG. 1. This is also referred to by one skilled in the art as being locked in battery or in a battery position.
Firing is split into two phases because the thrust vector existing between the bullet and the breech is under pressure in the barrel. Firing occurs in the M-1911 pistols when the grip safety is depressed, the trigger is squeezed, and the interaction of the trigger releases the hammer. The released hammer then transfers its energy to the internal firing pin, which, in turn, strikes the primer. As the primer ignites the propellant charge in the chambered cartridge, the hot powder gasses expand thus building pressure that forces the bullet down the barrel. As the gasses expand, the barrel 110 and slide 120 remain locked together both horizontally and vertically during the initial firing phase. Then as the bullet travels down the barrel shown in FIG. 3, the barrel begins to move rearward pivoting on the link and link pin 150,156.
At the end of the firing phase, the bullet exits the muzzle and drops gas pressure inside the barrel. Bullet departure breaks the balanced thrust vector established when the bullet was in the barrel 110. In terms of the effect on the pistol, this action enables the top locking lugs 155 to horizontally disengage and imparts a rearward force on the slide 120 assembly equal to the inertia of the departing bullet. Then, because the slide 120 assembly has a greater relative mass, and with the added benefit of the recoil spring, inertial energy is absorbed as the slide recoils to the rear. FIG. 3 shows a side projection cut away view of the Colt M-1911 shortly after firing and the bullet's exit from the barrel. In pistols with standard ordnance dimension barrels, barrel link-down and vertical locking lug disengagement begin momentarily after the lugs 155 horizontally disengage at zero breech pressure just after the firing of a chambered round.
As can be appreciated by one skilled in the art and as shown in FIG. 3, the barrel link 150 is coupled to the barrel 110 by a lug pin 152 and to the frame 170 by a slide stop pin 156. As the barrel 110 moves forward, the curved portion of the barrel lug 130 aids in forcing the barrel 110 into a full lock-up position. The barrel lug 130 (sometimes referred to as link lugs) in the M-1911 is an integral part of the barrel 110 that extends from the barrel to form two laterally spaced legs. The channel formed by the legs of the barrel lug 130 receives and supports the barrel link 150. The accuracy of the M-1911 is determined by the consistency at which the barrel 110 is placed into battery. As can be appreciated by one skilled in the art, each time the barrel is removed from battery to eject the expended casing and then placed back into battery with a new round, the placement of the barrel 110 with respect to the slide 120 and frame 170 may be slightly different. This inconsistency drives the ultimate accuracy of the weapon. A term known to one skilled in the relevant art for a measure of accuracy of a weapon is Minutes of Angle (“MOA”). One MOA is a mathematical term for 1/60th of an arc degree. 60 MOA=1 hour=1 deg. MOA measures the dispersion of a firing pattern at a certain range. One MOA at one hundred yards would be approximately 1 inch.
The accuracy of the M-1911 is inherently limited by the ability of barrel 110 to consistently achieve the same position in battery. This is reflected by its MOA. For example, if the barrel never left battery and was essentially a breech loaded single shot weapon, the MOA may be an order of magnitude smaller than that of a weapon in which the barrel is routinely disengaged and then reengaged into a battery position. The barrel link 150 is the primary means in the M-1911 by which the barrel is placed into battery, thus the vertical and horizontal movement of the barrel link 150 degrades the M-1911's accuracy. The link 150 acts as a single pivot point that transforms the forward motion of the barrel, as imparted to the barrel by the recoil of the slide, into a vertical motion so as to engage the lugs 155 and place the barrel into battery.
Furthermore, after repeated firings bearing stress, creep, due to the heat involved in repeated firings, and strain from the barrel link 150 and the pins coupling together slide 120, frame 170, and the barrel 110, reduces the ability of the link 150 to adequately and consistently place the barrel 110 into battery. After several hundred rounds of firing, the inherent accuracy of the weapon degrades and its MOA increases. The slide locking surfaces and those of the barrel 110 begin to degrade upon the first round fired. As a result, the economic life of the weapon is significantly reduced. Furthermore, accuracy is markedly lost in the first 250 rounds so as to make the firearm unable to perform as intended.